CN110998391A

CN110998391A - Optical coupling structure

Info

Publication number: CN110998391A
Application number: CN201880047084.0A
Authority: CN
Inventors: 亚伯拉罕·周; 保罗·毛-仁·吴
Original assignee: Ardot
Current assignee: Ardot; Adolite Inc
Priority date: 2017-05-19
Filing date: 2018-05-07
Publication date: 2020-04-10
Also published as: CN110998393A; WO2018213035A1; US10585250B2; WO2018213036A1; JP2020521186A; US20180335588A1; JP2020521187A; US20180335587A1; US10670816B2; US10222564B2; WO2018213040A1; US10436991B2; US20180335583A1; US20180335590A1; US10439720B2; US10439721B2; US20180337111A1; WO2018213038A1; US10545300B2; WO2018213042A1

Abstract

An exemplary structure has a single-mode polymer waveguide terminated at both ends with a lenticular coupling structure between an edge-emitting laser chip and a single-mode optical fiber. The edge-emitting laser is assembled on the bottom cladding of the waveguide front end, with a gap filled with an index matching structure, and has multiple layers of different index materials to achieve better matching efficiency. Another exemplary structure is a multi-channel polymer waveguide for transmitting optical signals from an edge-emitting laser array to a fiber array and receiving optical signals from the fiber array to a photodetector array. The multi-channel polymer waveguide is assembled with a multi-channel connector for connection to a fiber optic cable. The multi-channel polymer waveguide core is angled with respect to the waveguide axis direction to compensate for the difference in spacing between the edge-emitting laser channel and the single mode fiber in the fiber.

Description

Optical coupling structure

Cross Reference to Related Applications

The present application claims the priority of U.S. provisional patent application entitled "OPTICAL coupling structures" (application No. 62/508,940) filed on 19/5/2017 and entitled "OPTICAL INTERCONNECT MODULES" (application No. 62/509,892) filed on 23/5/2017, the contents of both provisional applications being incorporated herein by reference in their entirety.

Technical Field

The present invention relates to an optical coupling structure, and more particularly, to optical coupling of an edge-emitting diode.

Background

Cloud computing, enterprise networks and data center networks continue to drive the demand for optical fiber communication bandwidth for metro and long haul lines, and rack-to-rack lines in data centers, to 100Gbps and even higher. Such high capacity communication systems typically employ fiber optic transmission systems using Single Mode Fiber (SMF). Common fiber transmission systems include side (edge) emitting laser diodes, such as Distributed Feedback (DFB) lasers coupled to single mode fibers. Various coupling structures have been proposed to improve the coupling efficiency between a distributed feedback laser and a single mode optical fiber. These common coupling structures include butt coupling (direct alignment of the optical path) of a DFB laser to a single mode fiber SMF, integrating or using a combination of a cylindrical lens between the DFB and the waveguide and a graded index rod lens, and using a coupling structure similar to that described above between the waveguide and the SMF. However, these systems have the disadvantage of being bulky and costly to assemble. There is therefore a need for a more compact and efficient device to replace current interconnect optocouplers.

Disclosure of Invention

The present invention provides an optical coupling structure that connects a laser diode to a single mode optical fiber through a polymer waveguide. One embodiment of the light coupling structure comprises: a laser diode; a polymer waveguide comprising a waveguide structure comprised of a first polymer, a waveguide cladding structure comprised of a second polymer, a first end, a second end, a first integral lens at the first end, wherein the laser diode is aligned with the first integral lens; a connector aligned with the second end of the polymer waveguide, and a single mode optical fiber aligned with the connector.

Optionally, the laser diode is an edge-emitting DFB laser chip.

Optionally, the polymer waveguide is a single mode polymer waveguide.

Optionally, the optical coupling structure further comprises a first index matching structure located between the edge-emitting laser diode and the first end of the polymer waveguide, wherein the first index matching structure covers the first end of the polymer waveguide including the first integrally formed lens, the first index matching structure optionally including multiple layers of materials having different refractive indices.

Optionally, the light coupling structure further comprises a second integrally formed lens at the second end of the polymer waveguide.

The light coupling structure also includes a second index matching structure positioned between the connector and the polymer waveguide, the second index matching structure covering a second end of the polymer waveguide including a second integrally formed lens.

Alternatively, the first integrally formed lens at the first end of the polymer waveguide may be spherical.

Optionally, the waveguide cladding structure of the polymer waveguide may further comprise a bottom cladding layer on which the polymer waveguide structure is formed and a top cladding layer over and laterally surrounding the waveguide structure.

The bottom cladding includes a first bottom protrusion and the top cladding includes a first top protrusion. The first bottom protrusion and the first top protrusion are aligned with a first integral lens at a first end of the polymer waveguide.

Another embodiment discloses a multi-channel light coupling structure, comprising: a plurality of edge-emitting laser diodes; a plurality of multi-channel polymer waveguides comprising a plurality of polymer waveguide structures comprised of a first polymer and waveguide cladding structures comprised of a second polymer surrounding the plurality of polymer waveguide structures; a first end, a second end, a plurality of first integrally formed lenses aligned with the first end waveguide structure, wherein each of the plurality of laser diodes is aligned with one of the plurality of first integrally formed lenses and thus also with one of the waveguide structures; a multi-channel connector aligned with the second end of one of the multi-channel polymer waveguides; and a plurality of single mode optical fibers assembled in the optical fiber ribbon and aligned with the multi-channel connector. As a result, each edge-emitting laser is aligned end-to-end with a designated single-mode fiber.

Optionally, the plurality of laser diodes are edge-emitting DFB laser chips.

Optionally, the multi-channel polymer waveguide comprises a plurality of single-mode polymer waveguides.

According to another embodiment of the invention, the multi-channel light coupling structure further comprises a first index matching structure located between the plurality of emitting laser diodes and the first end of the multi-channel polymer waveguide, wherein the first index matching structure covers the first end of the multi-channel polymer waveguide including a first plurality of integrally formed lenses.

According to another embodiment of the invention, the multi-channel light coupling structure further comprises: a plurality of second integrally formed lenses at a second end of the multi-channel polymer waveguide, and a second index matching structure between the multi-channel connector and the multi-channel polymer waveguide, the second index matching structure covering the second end of the multi-channel polymer waveguide including the plurality of second integrally formed lenses.

According to another embodiment of the present invention, in a multi-channel light coupling structure, a plurality of waveguide structures in a multi-channel polymer waveguide are arranged at a plurality of angles to the waveguide axis to compensate for a spacing difference between the laser channels and single-mode fibers in the fiber optic ribbon. The plurality of angles is a multiple of θ, where θ is equal to a ratio of the difference in spacing to the axial length of the waveguide.

One embodiment of the present invention provides a manufacturing method comprising the key steps of: first, the waveguide structure of the polymer waveguide is lithographically etched by an etching process to a rib ridge on the plane of the bottom cladding layer, and then the top cladding layer is formed to surround the waveguide structure, thereby forming a buried channel waveguide.

Another embodiment of the present invention provides another manufacturing method, comprising the key steps of: first, a photosensitive polymer material is used as a waveguide structure of a polymer waveguide, which is lithographically etched by a photolithography process to form a ridge on the plane of a bottom cladding layer, and then a top cladding layer is formed to surround the waveguide structure, thereby forming a buried channel waveguide.

Another embodiment of the present invention provides another manufacturing method, including: first, a trench is formed in the bottom cladding layer, a waveguide structure is formed by filling the trench, and then the waveguide structure on the trench is covered to form the top cladding layer. A polishing or etching step may be required to remove excess waveguide material outside the trench.

The active optical device may include a Photodetector (PD) in the optical path that may replace the DFB laser shown to act as a receiver when light enters the waveguide from the back end fiber and the photodetector is located at the front end behind the lens and index matching material. Although photodetectors are shown in these figures, an inverse system with photodetectors or photodetector arrays may be similar to an active laser or laser array system.

Drawings

Having thus described some embodiments in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale.

Fig. 1 is a schematic cross-sectional structural view of an optical coupling structure integrating an edge-emitting laser, a polymer waveguide, and a single-mode optical fiber according to an embodiment of the present invention.

Fig. 2A is an isometric view of a polymer waveguide according to the embodiment shown in fig. 1.

Fig. 2B is an exploded isometric view of the polymer waveguide of fig. 2A according to the embodiment shown in fig. 1.

Fig. 2C is a schematic top view of a lens integrally formed with a laser or single mode fiber at a coupling interface of a waveguide or waveguide cladding according to the embodiment shown in fig. 1.

FIG. 3A is a schematic cross-sectional block diagram of a multi-channel light coupling structure according to another embodiment of the invention.

FIG. 3B is a schematic cross-sectional block diagram of one channel in the multi-channel light coupling structure according to the embodiment shown in FIG. 3A.

FIG. 4 is a companion circuit of an optical coupling structure according to an embodiment of the invention.

Detailed Description

Embodiments described herein provide a light coupling structure that connects an edge-emitting laser diode to a single-mode optical fiber through a polymer waveguide. More specifically, the present embodiments describe a Polymer Waveguide (PWG) and Flexible Printed Circuit (FPC) based optical coupling structure for optically coupling a laser diode (e.g., DFB laser chip) to a Single Mode Fiber (SMF). In one aspect, the polymer waveguide of the present embodiments can comprise an integrally formed microlens structure monolithically integrated with the polymer waveguide, while being fabricated using photolithographic etching techniques (e.g., photolithography and etching) that are widely used in the semiconductor industry. In this manner, the optical interconnect structure according to the current embodiment may improve optical coupling efficiency between the laser diode/photodetector and the single mode optical fiber without the need for additional external lenses for laser/polymer waveguide alignment and optical fiber components. This can simplify the optical configuration of the coupling structure and reduce the manufacturing cost.

In another aspect, the polymer waveguide of the optical coupling structure can be coupled to a connector, for example, a Mechanical Transmission (MT) connector. When connected to one end (back end) of a polymer waveguide and to a single mode fiber or a multimode fiber in a multi-channel optically coupled array device, a Mechanical Transmission (MT) connector is also known as a PMT connector. Sometimes, the optical coupling structure may be considered part of a flexible printed circuit based system.

In various embodiments, reference is made to the accompanying drawings. Certain embodiments, however, may be practiced without one or more of these specific details, or in combination with other known methods and configurations. The following description sets forth numerous specific details such as specific configurations, dimensions, processes, etc., in order to provide a thorough understanding of the embodiments. In other instances, well-known processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the embodiments. Reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, configuration, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase "in one embodiment" appearing in various places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments.

The term "as used herein. . . Upper "," across "," to "," on. . . And is between. . . The upper "may refer to the relative position of one layer with respect to the other layer. One layer "passes through", "across" or "on" another layer, or "adheres to" or "contacts" another layer, may be in direct contact with the other layer, or may have one or more intervening layers. A layer "between" multiple layers may be in direct contact with the layers, or may have one or more intervening layers.

Referring now to FIG. 1, FIG. 1 provides a schematic cross-sectional block diagram of an optical coupling structure for connecting a DFB laser to a single-mode fiber via a polymer waveguide, according to one embodiment. According to an embodiment, the optical coupling structure may be integrated on a Flexible Printed Circuit (FPC). Thus, the optical coupling structure may not include a single mode optical fiber, but rather be terminated with a connector, such as a mechanical transmission (PMT), that is designed to couple with one or more polymer waveguides.

As shown in fig. 1, the light coupling structure may include a polymer waveguide 100. A polymer waveguide is a light-transmitting device made of a polymer material that can direct intense beam light within the waveguide region in the 3-30 micron range by total internal reflection. The polymer waveguide 100 shown in fig. 1 has a polymer waveguide region 124 surrounded by a polymer cladding region 122, the refractive index of the polymer cladding region 122 being lower than the refractive index of the waveguide region 124. The polymer waveguide region may be a slab structure sandwiched between a top cladding layer and a bottom cladding layer, or a ribbon structure with a circular or rectangular cross-section surrounded by cladding rods. The polymer waveguide 124 is typically made of a polymer material (typically greater than 2.5) with a relatively high dielectric constant, such as polyimide, polystyrene, mylar, and electroactive polymers, among others. The polymer cladding 122 is typically made of a polymer material with a relatively low dielectric constant (typically less than 2.4), such as PTFE, polytetrafluoroethylene, polyethylene, polypropylene and electroactive polymers (with relatively low refractive indices). The polymer waveguide 100 has two ends, the front end is connected to an active light source 111 by an integrally formed lens, and the active light source 111 may include an edge-emitting laser diode or a Distributed Feedback (DFB) laser (or photodetector in a receiver device). The other end (or back end) is connected to a single mode optical fiber 140, either directly or through a connector 130. Although this is optional, providing a second integrally formed lens 128 at the second or back end of the polymer waveguide can improve coupling efficiency, if necessary. If the polymer waveguide is a slab structure, the top cladding layer, the bottom cladding layer, and the waveguide layer therebetween are formed as a slab structure. If the polymer waveguide is a ribbon structure, the high index waveguide may be molded or lithographically etched as ridges or grooves along the waveguide direction within the surrounding polymer cladding. The optical path of the edge-emitting laser 111 (e.g., DFB laser) is aligned with the first integral lens 127 at a first end or front end of the polymer waveguide 120. A connector 130 (e.g., a polymer mechanical transmission connector), optionally through an integrally formed lens 128, is aligned with the second or back end of the polymer waveguide 120. The front-end structure 125 and the back-end structure 126 between the front end of the polymer waveguide 120 and the laser diode/DFB laser 111 or between the back end of the polymer waveguide 120 and the connector 130 are filled with an index matching material. The front lens 127 and the back lens 128 are in direct contact with the index matching material in the

index matching structures

125 and 126. In some cases, the

lens

127 or 128 is integrally formed as an extension of the polymer waveguide structure 124, so that the index matching material is embedded in the outer surface of the lens 127/128. Similarly, when light enters the waveguide from a back end fiber and the photodetector is located at the front end behind the lens and index matching material, the optical path can be aligned with the photodetector (not shown in FIG. 1) which replaces the illustrated DFB laser for use as a receiver. An active device (e.g., DFB laser 111 or photodetector, etc.) may be assembled on the lower cladding at the first end (or front end) of the slab-like polymer waveguide while the gap of the structure 125 is filled with an index matching material. In use, the connector 130 may be coupled back to the single mode optical fiber 140 with the optical path exiting the polymer waveguide 120 aligned with the single mode optical fiber 140, optionally through the lens 128 and index matching structure 126 for better efficiency.

In one embodiment, a first index matching structure 125 may be formed between the edge-emitting laser diode/DFB laser 111/photodetector (not shown in fig. 1) and the first end (or front end) of the polymer waveguide 120. The first index matching structure 125 then covers the first end of the polymer waveguide including the first integrally formed lens 127. The first index matching structure 125 may also include one or more materials into the multilayer, although typically three layers. The purpose of index matching is to optimize the light transmission between the material forming the edge-emitting laser diode (e.g., DFB laser 111) and the material forming the waveguide 124, so the matching is gradual, or gradual of multiple materials. The same technique is also applied to the back-end index matching structure 126.

According to an embodiment, the second integrally formed lens 128 may alternatively be formed at the second end (or back end) of the polymer waveguide 120. Similarly, the second integral lens 128 may be integrally formed with the polymer waveguide 124. Additionally, a second index matching structure 126 may be located between the connector 130 and the back end of the polymer waveguide 120. A second index matching structure 126 covers a second end of the polymer waveguide 120, the polymer waveguide 120 including a second integrally formed lens 128 outer surface.

In an exemplary embodiment, the index matching structure 125/126 may be designed as a single layer structure having one refractive index, or may be designed as a multi-layer structure of multiple materials having multiple refractive indices, typically a three-layer structure having at least two reflectivities. For example, one material may be index matched to the waveguide structure 124, while another material may be index matched to the waveguide cladding structure 122.

Referring now to fig. 2A, fig. 2A provides an isometric view of the polymer waveguide 120 of the embodiment shown in fig. 1. Fig. 2B is an exploded isometric view of the polymer waveguide according to fig. 2A, and fig. 2C is a schematic top view of the waveguide and waveguide cladding of the polymer waveguide shown in fig. 2A according to an embodiment. As shown, the polymer waveguide 120 may include a waveguide 124, the waveguide 124 having a first end and a second end. The first integrally formed lens 127 may be located at a first end of the waveguide structure 124 and the second integrally formed lens 128 may be located at a second end of the waveguide structure 124. In the particular embodiment shown in fig. 2A-2C, the integrally formed lens 127/128 may be an extension of the waveguide structure and may be spherical. In the embodiment shown in fig. 2C, the width of the waveguide structure 124 along the optical path may be narrower than the ball lens 127/128. In one embodiment, the spherical lens may have a circular or cylindrical cross-section, but this is not required.

The polymer waveguide 120 may be formed from several layers. In one embodiment, the polymer waveguide 120 includes a bottom cladding layer 122b, a waveguide structure 124 on the bottom cladding layer 122b, and a top cladding layer 122t over and around the waveguide structure 124. For example, the bottom cladding layer 122b may be formed first, and then the waveguide structure 124 may be deposited and lithographically etched over the bottom cladding layer 122 b. In one embodiment, the waveguide structure 124 has a flat top surface adjacent the top cladding layer 122t and a flat bottom surface adjacent the bottom cladding layer 122 b. After the photolithographic etching of the waveguide structure 124, a top cladding layer 122t may be formed on the photolithographic etched waveguide structure 124 and the bottom cladding layer 122 b. The bottom cladding layer 122b, the waveguide structure 124, and the polymer waveguide 122t may then be lithographically etched together. For example, a first edge (front side where incident light arrives) and a second edge (back side where light exits) of the polymer waveguide 120 may be formed using a photolithography-dry etching technique.

Fig. 2B is an exploded 3D view of the polymer waveguide, with the bottom cladding 122B including a first bottom protrusion 129, and the top cladding 122t including a first top protrusion 129, both aligned with the first integral lens 127 along the first edge. In one embodiment, the first bottom tab and the first top tab 129 along the first edge may be semi-cylindrical. As shown in fig. 2C, the semi-cylindrical shape may be attributed to only a portion of the ball lens 127/128 extending along the first edge, with other portions contained within the polymer waveguide 120.

The polymer cladding 122t may be deposited in a waveguide-preferential deposition process around and over the polymer waveguide structure 124, with the polymer core material first deposited as a layer and lithographically etched as a rib ridge on a plane on the bottom cladding 122 b. It can also be deposited in a cladding trench-first process by two separate deposition steps: the bottom cladding layer 122b is first deposited and the trench is prepared and filled with the waveguide structure 124, and then a second deposition is performed on the bottom cladding layer 122b to cover the waveguide structure 124. The second trench-first process may require a planarization process to remove waveguide material outside the trench region after the cladding layer is deposited.

Similar to the protrusion 129, the bottom cladding layer 122b may also include a second bottom protrusion and the top cladding layer includes a second top protrusion, both aligned with the second integrally formed lens 128 along the second edge. In one embodiment, the second bottom protrusion and the second top protrusion along the second edge are semi-cylindrical. The second protrusion is not shown in any of fig. 2A-2C, as it is similar to protrusion 129.

According to an embodiment, index matching structures 125 and 126 (126 not shown here) may be formed at the first and second edges of the polymer waveguide. The index matching material in the index matching structure 125/126 is formed around the lens 127/128. The index matching structure may facilitate matching of the indices of refraction of adjacent layers in butt-coupling techniques, where the optical paths of adjacent layers may be seamlessly aligned. Although only a single index matching structure is shown in fig. 2A-2B, it should be understood that a second index matching structure may be formed on the opposite edge of the polymer waveguide. In one embodiment, a first index matching structure is formed on a first edge of polymer waveguide 120, spanning bottom cladding 122b, top cladding 122t, and waveguide structure 124 including first bottom protrusion 129, first integral lens 127, and first top protrusion 129. In one embodiment, a second index matching structure is formed on a second edge of the polymer waveguide 120, spanning the bottom cladding 122b, the top cladding 122t, and the waveguide structure 124 including a second bottom protrusion 129, a second integrally formed lens 128, and a second top protrusion 129. In an exemplary embodiment, the index matching structure may also include one or more materials, typically three layers, having at least two different indices of refraction. The particular embodiment shown includes three layers that are aligned with the bottom cladding layer 122b, the waveguide structure 124, and the top cladding layer 122t, respectively, to provide a particular index matching for the waveguide structure and the waveguide cladding structure. Note that in fig. 2A and 2B, the slab shape of the index matching structure 125 is much wider than the lens 127 being integrally formed, and the width of the index matching structure 125 may be just around the outer surface of the lens 127 to ensure proper light transmission efficiency.

Although the integrally formed

lenses

127 and 128 shown in fig. 2A-2C are extensions of the polymer waveguide structure 124, the coupling lens need not be formed as part of the polymer waveguide structure. In another embodiment, the coupling lens may be a structure that is fabricated separately from the polymer waveguide 124 in a single-piece formation process, which may include separate deposition and photolithographic etching processes.

According to embodiments, an optical coupling structure for one channel may include one or more optical channels, and a connector (e.g., a PMT connector) that connects to one or more single mode optical fibers (SMFs) in a single or multi-channel configuration. Fig. 3A is a schematic cross-sectional top view of a multi-Channel (CH) light coupling structure 300 according to an embodiment of the invention. Fig. 3B is a schematic cross-sectional top view of a single-Channel (CH) light coupling structure illustrating one channel of the multi-channel light coupling structure of fig. 3A.

FIG. 3a is a top view of a multi-channel optical coupler system 300 employing polymer waveguides. The system 300 includes an array 311A of laser diodes or DFB lasers, an array 320A of polymer waveguides, an array 330A of connectors, and an array 340A of single mode fiber bundles. Polymer waveguide array 320A includes a multi-waveguide array 324A that defines a plurality of optical paths formed in cladding array 322A. As illustrated in fig. 2A-2C, the cladding array may have a bottom piece and a top piece that may be fabricated in a variety of ways to enclose the array of polymer waveguide structures within the cladding material 322A. In addition, the multi-channel light coupling structure 320A also includes a plurality of first integrally formed lens arrays 327A at a first end (or front end) of the polymer waveguide array 320A to align with the edge-emitting laser diode array or DFB laser array 311A. In a multi-channel receiver system, a photodetector array may replace the laser array 311A. The connector array 330A (e.g., PMT connector) is designed to couple to a plurality of single mode fiber arrays 340A. Similar to the single-channel polymer waveguide, the index matching material in the index matching structure 325A/326A is formed around the front end lens array 327A and the back end array lens 328A. The index matching structure may facilitate matching of the indices of refraction of adjacent layers in butt-coupling techniques, wherein the optical paths of adjacent layers in multiple passes may be seamlessly aligned.

In the exemplary embodiment, optical coupling system 300 is a four-channel structure including four DFB lasers assembled in DFB laser array 311A and four optical paths connecting individual fibers in single-mode fiber bundle array 340A.

Thus, the array of structures may be formed similarly as described in FIGS. 2A-2C, plus a plurality of waveguide structures and a plurality of lenses that are lithographically etched. The formation of the index matching structure may also be in a similar fashion.

Thus, a multi-channel polymer waveguide according to embodiments may transmit optical signals from a DFB laser to an array of optical fibers and receive optical signals from the optical fibers to an array of photodetectors. Such multi-channel polymer waveguides may be assembled with multi-channel PMT connectors for connection to fiber bundle arrays or ribbon cables.

In one embodiment, the laser diode or DFB laser array has a typical laser-to-laser pitch of 1, greater than 250 μm, and the single-mode fiber optic ribbon cable has a typical fiber-to-fiber pitch of 2, 250 μm, which results in a slight misalignment when multiple waveguide structures are parallel to each other. Therefore, a tilt angle (θ) is introduced to shift the waveguide. For example, θ 1 is 3 θ, θ 2 is 2 θ, θ 3 is θ, and θ 4 is 0 °. The angle of inclination theta being equal to tan^-1(50 μm/L), and L is the total axial length of the waveguide.

In another embodiment, the plurality of waveguides may be slightly curved to accommodate the position of the waveguides.

FIG. 3B illustrates one of the plurality of channels in the light coupling structure, according to the embodiment disclosed in FIG. 3A. The optical coupler comprises a laser diode or DFB laser 311, the laser signal is coupled into the polymer waveguide 320 through a lens 327 and an index matching material 325. The polymer cladding 322 and the polymer waveguide structure 324 guide the laser signal to an exit end lens 328 and an enclosed index matching material 326, and the transmitted light enters a single mode optical fiber 340 via a connector 330 (e.g., a PMT connector). A tilt angle (theta) is built into the polymer waveguide structure to compensate for the difference in spacing between the standard laser channel and the standard fiber ribbon channel in a multi-channel optical coupler system.

Referring to fig. 4, the electrical form factor 410 may be a Flexible Printed Circuit (FPC) board based device mounted near the polymer waveguide. The FPC device supports a plurality of high speed electrical traces (transmission lines) 450, RF transmission lines, a driver IC421 connected to a laser diode or DFB laser array 411A or photodiode array (not shown), and a receiver IC435 (e.g., transimpedance amplifier) connected to a mechanical transmission connector 430. An exemplary data rate for the optical coupling structures described herein may be 25 gigabits per second (Gbps) per channel and may be extended to higher rates, such as 50Gbps per channel.

Combinations or variations of the above embodiments are obviously possible for the skilled person for manufacturing the optical coupling structure when using the various aspects of the embodiments. Although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the appended claims are not necessarily limited to the specific features or acts described. The specific features and acts disclosed are to be understood as example embodiments useful for interpreting the claims.

Claims

1. A light coupling structure, comprising:

a laser diode;

a polymer waveguide comprising a waveguide structure made of a first polymer, a waveguide cladding structure made of a second polymer, a first end, a second end, and a first integrally formed lens at the first end, wherein the laser diode is aligned with the first integrally formed lens;

a connector aligned with the second end of the polymer waveguide; and

a single mode optical fiber aligned with the connector.

2. The light coupling structure of claim 1, wherein the laser diode is an edge-emitting laser chip.

3. The light coupling structure of claim 1, wherein the polymer waveguide is a single-mode or multi-mode polymer waveguide.

4. The light coupling structure of claim 1, further comprising a first index matching structure located between the laser diode and the polymer waveguide first end, wherein the first index matching structure covers the polymer waveguide first end including the first integrally formed lens.

5. The light coupling structure of claim 4, wherein the first index matching structure comprises multiple layers of material, each layer of material having a different index of refraction.

6. The light coupling structure of claim 1, further comprising a second integrally formed lens at a second end of the polymer waveguide.

7. The light coupling structure of claim 6, further comprising a second index matching structure located between the connector and the polymer waveguide, wherein the second index matching structure covers a second end of the polymer waveguide including the second integrally formed lens.

8. The light coupling structure of claim 1, wherein the first integral lens is convex.

9. The light coupling structure of claim 1, wherein the waveguide cladding structure of the polymer waveguide further comprises a bottom cladding layer and a top cladding layer, the waveguide structure being formed on the bottom cladding layer, and the top cladding layer being positioned above and laterally surrounding the waveguide structure.

10. The light coupling structure of claim 9, wherein the bottom cladding layer comprises a first bottom protrusion and the top cladding layer comprises a first top protrusion, the first bottom protrusion and the first top protrusion being aligned with the first integrally formed lens.

11. A multi-channel light coupling structure comprising:

a plurality of laser diodes;

a multi-channel polymer waveguide comprising a plurality of waveguide structures made of a first polymer, waveguide cladding structures made of a second polymer, a first end, a second end, and a plurality of first integrally formed lenses at the first end, wherein the plurality of laser diodes are aligned with the plurality of first integrally formed lenses;

a multi-channel connector aligned with the second end of the multi-channel polymer waveguide; and

a plurality of single mode optical fibers assembled in the optical fibers and aligned with the multi-channel connector.

12. The multi-channel light coupling structure of claim 11, wherein the plurality of laser diodes are edge-emitting laser chips.

13. The multi-channel light coupling structure of claim 11, wherein the multi-channel polymer waveguide comprises a plurality of single-mode or multi-mode polymer waveguides.

14. The multi-channel light coupling structure of claim 11, further comprising a first index matching structure located between the plurality of laser diodes and the multi-channel polymer waveguide first end, wherein the first index matching structure covers the first end of the multi-channel polymer waveguide including the plurality of first integrally formed lenses.

15. The multi-channel light coupling structure of claim 11, further comprising a second plurality of integrally formed lenses at the second end of the multi-channel polymer waveguide.

16. The multi-channel light coupling structure of claim 15, further comprising a second index matching structure located between the multi-channel connector and the multi-channel polymer waveguide, wherein the second index matching structure covers a second end of the multi-channel polymer waveguide including the plurality of second integrally formed lenses.

17. The multi-channel light coupling structure of claim 11, wherein the plurality of waveguide structures in the multi-channel polymer waveguide are arranged to form a plurality of angles with the waveguide axis to compensate for a pitch difference between the laser channel and the single-mode fiber in the optical fiber, the plurality of angles being a multiple of θ (θ -pitch difference/waveguide length).

18. A method of forming the light coupling structure of claim 11, first, the waveguide structure of the polymer waveguide is lithographically etched into a line structure at the bottom cladding plane, and then a top cladding layer is formed overlying the waveguide structure.

19. A method of forming the light coupling structure of claim 11, first forming a trench in the bottom cladding layer, forming the waveguide structure to fill the trench, and forming the top cladding layer overlying the waveguide structure.

20. A method of forming the light coupling structure of claim 19, further comprising a planarization process for removing excess waveguide structure outside the bottom cladding trench.